In the technique of the sector devices are already known for preparing portions of meat and other flowable food product based on the arrangement of two cylinders provided with pistons and means for alternately communicating one of the said cylinders with an inlet for the said meat or other flowable food product and the other of the said cylinders having an outlet for expelling a portion of food product and vice versa. The incoming product is driven by a pump and when it is entering in the related cylinder it moves the respective piston a determined length depending on the size of the portions to be obtained. Effectively, the size of the portion is equivalent to the volume of a stroke of the piston, that is to say, the volume which results from multiplying the internal surface of the cylinder cross section by the length of the piston working stroke. To expel the portion food product from the cylinder, the piston is driven in the opposite direction by means of a fluid dynamic drive. To delimit the said working stroke of the said pistons, means having adjustable stops are provided for moving the piston rods, in order to accurately determine this way the size of the said portions.
U.S. Pat. No. 5,029,735 by Wendell E. Dennis, filed on 20 Sep. 1989, discloses a device of this kind, also called a “turret”, in which two of the said cylinders (although it could be only one) are mounted in raised position on an assembly which can be alternately rotated in a predetermined angle, concretely 90°, in both directions to successively face the entrances of both cylinders with two inlet ducts and two outlet ducts. To make its cleaning inside the cylinders and the inlet and outlet ducts easier, a fluid dynamic device of cylinder and piston lifts the whole assembly in which portioning cylinders are mounted leaving free the entrances thereof and the entrances of the said ducts associated to them, for cleaning. However, such arrangement makes necessary a nonstop angular stroke of the whole cylinder assembly, which carries unwanted dynamic effects and a high power consumption. The existence of only one or two portioning cylinders makes the production speed relatively low. In addition, the separation provided by the lifting device between the cylinder entrances and the inlet and outlet entrances of the ducts results insufficient to carry out a thorough and easy cleaning thereof.
WO 99/62766 of this applicant filed on 3 Jun. 1999 prior to a Spanish patent of 4 Jun. 1998, discloses a volumetric dosing device for pasty product for filling a canning line by thermoforming comprising at least a dosing cylinder, preferably two dosing cylinders, of above described kind, arranged parallel to each other raised at a static location, with its entrances at the lower part. The said entrances communicate with openings located on a cylindric wall of a hollow housing, arranged under the said dosing cylinders, for a valve body or chest which is driven to tightly rotate a given angle within the said housing, alternately in both directions. The said cylindric housing comprises an inlet of pasty product at an axial end thereof, and two outlets are arranged on its cylindric wall, at a substantially radial position, facing the said entrances of the dosing cylinders. On the other hand, the said valve chest is formed by a cylindric block provided on its periphery with a slotting extending in a generating line direction communicating through a passageway with an inlet opening at an axial end of the valve chest. Through holes fully cross the said bloc in a substantially radial direction without interfering with the said slotting. At a first angular position, the said valve chest alternately communicates the said inlet of pasty product with the entrances of the dosing cylinders through the said slotting and then, at a second angular position, the said entrances of the dosing cylinders with the said through holes. The assembly of dosing cylinders, with their related means to adjust the stroke of their pistons can be tilted with respect to the cylindric housing for cleaning the interior of the dosing cylinders and in addition, the said housing had an opening with an openable cover on its free axial end through which the valve chest can be withdrawn for cleaning it. The production speed of the said device greatly higher that of the above mentioned patent by Dennis due to the fact that the cylinders remain at a static position while only an alternate angular stroke of a slight valve body or chest typically of a plastic material. The accessibility of the areas to be cleaned is also significantly best. However, the existence of only one or two dosing cylinders still limits the production speed to moderated values.
The further application for a patent ES 200001136, also of this applicant, offers a series of improvements to the said valve chest which essentially consist in replacing the said through holes by a single incut having a space wider than that occupied by the said holes. The said incut carries a simplification of the dosing cylinder piston system which in the former model was a double piston with a first piston travelling within the dosing cylinder and a second piston travelling through the holes of the valve chest. This implies a significant improvement as for the mechanical simplification of the device although it has a little incidence as for the production speed.